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CVE-2025-21658 Detail

Description

In the Linux kernel, the following vulnerability has been resolved: btrfs: avoid NULL pointer dereference if no valid extent tree [BUG] Syzbot reported a crash with the following call trace: BTRFS info (device loop0): scrub: started on devid 1 BUG: kernel NULL pointer dereference, address: 0000000000000208 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 106e70067 P4D 106e70067 PUD 107143067 PMD 0 Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 1 UID: 0 PID: 689 Comm: repro Kdump: loaded Tainted: G O 6.13.0-rc4-custom+ #206 Tainted: [O]=OOT_MODULE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022 RIP: 0010:find_first_extent_item+0x26/0x1f0 [btrfs] Call Trace: <TASK> scrub_find_fill_first_stripe+0x13d/0x3b0 [btrfs] scrub_simple_mirror+0x175/0x260 [btrfs] scrub_stripe+0x5d4/0x6c0 [btrfs] scrub_chunk+0xbb/0x170 [btrfs] scrub_enumerate_chunks+0x2f4/0x5f0 [btrfs] btrfs_scrub_dev+0x240/0x600 [btrfs] btrfs_ioctl+0x1dc8/0x2fa0 [btrfs] ? do_sys_openat2+0xa5/0xf0 __x64_sys_ioctl+0x97/0xc0 do_syscall_64+0x4f/0x120 entry_SYSCALL_64_after_hwframe+0x76/0x7e </TASK> [CAUSE] The reproducer is using a corrupted image where extent tree root is corrupted, thus forcing to use "rescue=all,ro" mount option to mount the image. Then it triggered a scrub, but since scrub relies on extent tree to find where the data/metadata extents are, scrub_find_fill_first_stripe() relies on an non-empty extent root. But unfortunately scrub_find_fill_first_stripe() doesn't really expect an NULL pointer for extent root, it use extent_root to grab fs_info and triggered a NULL pointer dereference. [FIX] Add an extra check for a valid extent root at the beginning of scrub_find_fill_first_stripe(). The new error path is introduced by 42437a6386ff ("btrfs: introduce mount option rescue=ignorebadroots"), but that's pretty old, and later commit b979547513ff ("btrfs: scrub: introduce helper to find and fill sector info for a scrub_stripe") changed how we do scrub. So for kernels older than 6.6, the fix will need manual backport.


Metrics

NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 3.x Severity and Vector Strings:

NIST CVSS score
NIST: NVD
Base Score:  5.5 MEDIUM
Vector:  CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

References to Advisories, Solutions, and Tools

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Hyperlink Resource
https://git.kernel.org/stable/c/24b85a8b0310e0144da9ab30be42e87e6476638a Patch 
https://git.kernel.org/stable/c/6aecd91a5c5b68939cf4169e32bc49f3cd2dd329 Patch 
https://git.kernel.org/stable/c/aee5f69f3e6cd82bfefaca1b70b40b6cd8f3f784 Patch 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-476 NULL Pointer Dereference cwe source acceptance level NIST  

Known Affected Software Configurations Switch to CPE 2.2

Configuration 1 ( hide )
 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
   Show Matching CPE(s)
From (including)
5.11
Up to (excluding)
6.6.72
 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
   Show Matching CPE(s)
From (including)
6.7
Up to (excluding)
6.12.10
 cpe:2.3:o:linux:linux_kernel:6.13:rc1:*:*:*:*:*:*
   Show Matching CPE(s)
 cpe:2.3:o:linux:linux_kernel:6.13:rc2:*:*:*:*:*:*
   Show Matching CPE(s)
 cpe:2.3:o:linux:linux_kernel:6.13:rc3:*:*:*:*:*:*
   Show Matching CPE(s)
 cpe:2.3:o:linux:linux_kernel:6.13:rc4:*:*:*:*:*:*
   Show Matching CPE(s)
 cpe:2.3:o:linux:linux_kernel:6.13:rc5:*:*:*:*:*:*
   Show Matching CPE(s)
 cpe:2.3:o:linux:linux_kernel:6.13:rc6:*:*:*:*:*:*
   Show Matching CPE(s)

Denotes Vulnerable Software
Are we missing a CPE here? Please let us know.

Change History

2 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2025-21658
NVD Published Date:
01/21/2025
NVD Last Modified:
01/22/2025
Source:
kernel.org